JP5993098B2 - Method and apparatus for applying security information in a wireless communication system - Google Patents

Description

  The present invention relates to wireless communication, and more particularly, to a method and apparatus for applying security information in a wireless communication system.

  UMTS (universal mobile telecommunications system) is based on European system (European system), GSM (global system for mobile communications), and GPRS (general packet) generation is an asynchronous mobile communication system. The UMTS long-term evolution (LTE) is under discussion by 3GPP (3rd generation partnership project), which standardizes UMTS.

  3GPP LTE is a technology for enabling high-speed packet communication. A number of schemes have been proposed to reduce costs for users and operators, improve service quality, expand coverage, and increase system capacity, which are LTE targets. 3GPP LTE demands cost savings per bit, improved service usability, flexible use of frequency bands, simple structure, open interface and appropriate power consumption of terminals as higher level requirements.

  Small cells that use low power nodes are considered promising, especially as a way to build hot spots indoors and outdoors to cope with terminal traffic surges. A low power node generally means that the transmit power is less than the type of power such as macro nodes and base stations. For example, this corresponds to a pico base station and a femto base station. The small cell enhancement of 3GPP LTE is to focus on additional functionality that uses low power nodes in indoor and outdoor hotspot areas to improve performance.

  Some activities are to focus on achieving a higher degree of coordination between macros and low power layers, including different forms of macro assistance for low power and dual layer connections. . Dual connection means that the device has a connection at the same time as the macro and low power hierarchy. Macro support including dual connections can provide several advantages.

  -Improved mobility support: maintain mobility anchor points in the macro hierarchy and not only maintain soft mobility between the low power hierarchy nodes, but also soft mobility between the macro hierarchy and the low power hierarchy. Can also be maintained.

  -Low transmission overhead in the low power layer: for example, by transmitting only the information necessary for the individual user experience, it is possible to avoid the overhead that comes from idle-mode mobility support in the local region layer. is there.

  Energy efficient load balancing: When data transmission is not performed, it is possible to turn off the low power node to reduce the energy consumption of the low power hierarchy.

  -Link-specific optimization: Node selection can be optimized for each link by making it possible to select separate end points for the uplink and downlink.

  Various changes in the 3GPP LTE radio protocol are required for dual connection support. For example, when a double connection is introduced, a method of applying security information may be required.

  The present invention provides a method and apparatus for applying security information in a wireless communication system. The present invention provides a method for applying security information in a dual connection. In addition, the present invention provides a method for applying different security information to different radio bearer sets provided by a master eNB (MeNB; master eNodeB) and a secondary eNB (SeNB; secondary eNB).

  In one embodiment, a method for applying security information by a user equipment (UE) in a wireless communication system is provided. The method obtains first security information and second security information, and the first security information is provided by a first radio bearer (RB) set provided by a master eNB (MeNB; master eNodeB). And applying the second security information to a second radio bearer set provided by a secondary eNB (SeNB; secondary eNB).

  The first security information includes at least one of a first security parameter and a first security key, and the second security information includes a second security parameter and a second security key. Including at least one of them.

  The method further includes deriving the first security key based on the first security parameter.

The first security key is K _RRCint , K _RRCenc or K _UPenc for the _MeNB .

  The method further includes deriving the second security key from the first security key along with the first security parameter.

The second security key is K _RRCint , K _RRCenc or K _UPenc for the _SeNB .

  Obtaining the first security information is receiving the first security information from the MeNB via a security mode command message.

  Obtaining the second security information is receiving the second security information from the MeNB via a security mode command message.

  The first security information is applied to one or more cells of the MeNB.

  The second security information is applied to one or more cells of the SeNB.

  The terminal makes a first connection with the MeNB for signaling.

  The first connection is an RRC (radio resource control) connection.

  The terminal makes a second connection with the SeNB for user traffic.

  The second connection is an L2 connection.

  In another embodiment, a user equipment (UE) in a wireless communication system is provided. The terminal includes an RF (radio frequency) unit that transmits or receives a radio signal and a processor connected to the RF unit, wherein the processor acquires first security information and second security information, and 1 security information is applied to a first radio bearer (RB) set provided by a master eNB (MeNB; master eNodeB), and the second security information is provided by a secondary eNB (SeNB; secondary eNB) This is applied to the second radio bearer set.

  Security information can be efficiently applied in a double connection.

The structure of an LTE system is shown. Fig. 2 shows the radio interface protocol of the LTE system for the control plane. Fig. 2 shows the radio interface protocol of the LTE system for the user plane. An example of a physical channel structure is shown. A scenario in which small cells are placed inside / outside the macro area is shown. Fig. 5 illustrates key derivation for AS security and NAS security excluding handover. Indicates the initial activation of AS security. Indicates a dual connection scenario. 2 shows an example of a method for applying security information according to an embodiment of the present invention. FIG. 6 shows how a terminal and a MeNB according to an embodiment of the present invention generate a security key for a radio resource block between a terminal and a macro cell. FIG. FIG. 6 shows how a terminal and a SeNB according to an embodiment of the present invention generate a security key for a radio resource block between a terminal and a small cell. FIG. 1 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.

  The following technologies, CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), etc. It can be used for various wireless communication systems. CDMA can be implemented with a radio technology such as UTRA (Universal Terrestrial Radio Access) or CDMA2000. TDMA may be implemented by a radio technology such as GSM (global system for mobile communications) / GPRS (general packet radio services) / EDGE (enhanced data rates for GSM evolution). OFDMA is a wireless technology such as IEEE (institute of electrical and electrical engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, E-UTRA (evolved UTRA), etc. Can do. IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is a part of UMTS (Universal Mobile Telecommunications System). 3GPP (3rd generation partnership project) LTE (long term evolution) is E-UMTS (evolved UMTS), part of E-UMTS (evolved UMTS) using E-UTRA (evolved-UMTS terrestrial radio access) Adopt SC-FDMA in the uplink. LTE-A (advanced) is an evolution of 3GPP LTE.

  For clarity of explanation, LTE-A is mainly described, but the technical idea of the present invention is not limited to this.

  FIG. 1 shows the structure of an LTE system. A communication network is widely installed to provide various communication services such as Internet telephone (VoIP) via IMS and packet data.

  Referring to FIG. 1, the LTE system structure includes one or more terminals (UE) 10, an E-UTRAN (evolved-UMTS terrestrial radio access network), and an EPC (evolved packet core). The terminal 10 is a communication device that is moved by a user. The terminal 10 may be fixed or mobile, and may be other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device (wireless device). Sometimes called.

  The E-UTRAN can include one or more eNBs (evolved node-B) 20, and a plurality of terminals can exist in one cell. The eNB 20 provides the terminal points of the control plane and the user plane to the terminal. The eNB 20 generally means a fixed station that communicates with the terminal 10, and may be called by other terms such as BS (base station), BTS (base transceiver system), and access point (access point). . One eNB 20 can be arranged for each cell. There can be one or more cells in the coverage of the eNB 20. One cell is configured to have one of bandwidths such as 1.25, 2.5, 5, 10, and 20 MHz, and the downlink (DL) or the uplink (UL) is transmitted to a plurality of terminals. uplink) transmission service can be provided. At this time, different cells may be set to provide different bandwidths.

  Hereinafter, DL means communication from the eNB 20 to the terminal 10, and UL means communication from the terminal 10 to the eNB 20. In DL, the transmitter is part of the eNB 20 and the receiver is part of the terminal 10. In the UL, the transmitter is a part of the terminal 10 and the receiver is a part of the eNB 20.

  The EPC may include an MME (mobility management entity) responsible for the function of the control plane, and an S-GW (system architecture evolution (SAE) gateway) responsible for the function of the user plane. The MME / S-GW 30 is located at the end of the network and is connected to an external network. The MME has information on terminal access information and terminal capability, and such information can be mainly used for mobility management of the terminal. The S-GW is a gateway having E-UTRAN as a termination point. The MME / S-GW 30 provides the terminal 10 with a session termination point and a mobility management function. The EPC may further include a PDN (packet data network) -GW (gateway). The PDN-GW is a gateway having a PDN as a termination point.

  MME is NAS (non-access stratum) signaling to eNB 20, NAS signaling security, AS (access stratum) security control, inter CN (core network) node signaling for mobility between 3GPP access networks, idle mode terminal arrival Possibility (including control and execution of paging retransmission), tracking region list management (for terminals in idle mode and activation mode), P-GW and S-GW selection, MME for handover with MME change Bearer management functions including SGSN (serving GPRS support node) selection, roaming, authentication, dedicated bearer configuration for selection, 2G or 3G 3GPP access network handover PWS (public warning system: including the earthquake / tsunami warning system (ETWS) and a commercial mobile alert system (CMAS)) to provide a variety of functions, such as sending messages support. The S-GW host performs packet filtering (for example, through deep packet inspection), lawful blocking, terminal IP (Internet protocol) address allocation, transport level packing marking in DL, UL / It provides various functions for DL service level charging, gating and class enforcement, and DL class enforcement based on APN-AMBR. For clarity, the MME / S-GW 30 is simply expressed as a “gateway”, which can include both the MME and the S-GW.

  An interface for user traffic transmission or control traffic transmission can be used. The terminal 10 and the eNB 20 can be connected by a Uu interface. The eNBs 20 can be connected to each other via an X2 interface. The neighboring eNB 20 can have a mesh network structure with an X2 interface. The eNB 20 can be connected to the EPC through the S1 interface. The eNB 20 can be connected to the MME via the S1-MME interface, and can be connected to the S-GW via the S1-U interface. The S1 interface supports a many-to-many-relation between the eNB 20 and the MME / S-GW 30.

  The eNB 20 selects a gateway 30, routing to the gateway 30 during RRC (radio resource control) activation, scheduling and transmission of paging message, scheduling and transmission of BCH (broadcast channel) information, UL and DL Resource allocation from UE to terminal 10, eNB measurement configuration and provisioning, radio bearer control, RAC (radio admission control), and LTE active state can perform connection mobility control function . As described above, the gateway 30 can perform paging start, LTE idle state management, user plane encryption, SAE bearer control, and NAS signaling encryption and integrity protection functions by EPC.

  FIG. 2 shows the radio interface protocol of the LTE system for the control plane. FIG. 3 shows the radio interface protocol of the LTE system for the user plane.

  The layer of the radio interface protocol between the terminal and E-UTRAN is based on L1 (first layer) and L2 (second layer) based on the lower three layers of the OSI (open system interconnection) model widely known in communication systems. ) And L3 (third hierarchy). The radio interface protocol between the terminal and the E-UTRAN can be horizontally divided into a physical layer, a data link layer, and a network layer, and vertically, It can be divided into a control plane that is a protocol stack for transmitting a control signal and a user plane that is a protocol stack for transmitting data information. The hierarchy of the radio interface protocol can exist in a pair between the terminal and the E-UTRAN, which can be responsible for data transmission of the Uu interface.

  A physical layer (PHY) belongs to L1. The physical layer provides an information transfer service to an upper layer through a physical channel. The physical layer is connected to a higher layer MAC (media access control) layer via a transport channel. The physical channel is mapped to the transport channel. Data can be transmitted between the MAC layer and the physical layer through the transport channel. Data can be transmitted using radio resources through physical channels between different physical layers, that is, between the physical layer of the transmitter and the physical layer of the receiver. The physical layer can be modulated using an OFDM (orthogonal frequency division multiplexing) scheme, and uses time and frequency as radio resources.

  The physical layer uses a number of physical control channels. PDCCH (physical downlink control channel) is a resource allocation of PCH (paging channel) and DL-SCH (downlink shared channel), HARQ (hybrid autorepeat) related to DL-SCH. . The PDCCH may transmit an uplink grant to report to the terminal about resource allocation for uplink transmission. PCFICH (physical control format indicator channel) informs the terminal of the number of OFDM symbols used for PDCCH, and is transmitted for every subframe. A PHICH (physical hybrid ARQ indicator channel) transmits a HARQ ACK (acknowledgement) / NACK (non-acknowledgement) signal for UL-SCH transmission. A PUCCH (physical uplink control channel) transmits HARQ ACK / NACK for downlink transmission, a scheduling request, and UL control information such as CQI. PUSCH (physical uplink shared channel) transmits UL-SCH (uplink shared channel).

  FIG. 4 shows an example of a physical channel structure.

  The physical channel includes a plurality of subframes in the time domain and a plurality of subcarriers in the frequency domain. One subframe is composed of a plurality of symbols in the time domain. One subframe is composed of a plurality of resource blocks (RBs). One resource block includes a plurality of symbols and a plurality of subcarriers. In addition, each subframe can use a specific subcarrier of a specific symbol of the corresponding subframe for PDCCH. For example, the first symbol of the subframe can be used for PDCCH. The PDCCH can transmit dynamically allocated resources such as PRB (physical resource block) and MCS (modulation and coding schemes). A transmission time interval (TTI), which is a unit time during which data is transmitted, is the same as the length of one subframe. The length of one subframe is 1 ms.

  Transport channels are classified into common transport channels and dedicated transport channels depending on whether the channels are shared. A DL transport channel (DL transport channel) that transmits data from the network to the terminal is a BCH (broadcast channel) that transmits system information, a PCH (paging channel) that transmits a paging message, a DL that transmits user traffic or a control signal. -Includes SCH and the like. DL-SCH supports dynamic link adaptation and dynamic / semi-static resource allocation with changes in HARQ, modulation, coding and transmit power. DL-SCH also allows the use of broadcast and beamforming throughout the cell. System information carries one or more system information blocks. All system information blocks can be transmitted in the same period. An MBMS (multimedia broadcast / multicast service) traffic or control signal is transmitted via an MCH (multicast channel).

  The UL transport channel that transmits data from the terminal to the network includes an RACH (Random Access Channel) that transmits an initial control message, an UL-SCH that transmits user traffic or a control signal, and the like. UL-SCH can support dynamic link adaptation with HARQ and transmit power and potential modulation and coding changes. UL-SCH also allows the use of beamforming. RACH is generally used for initial access to a cell.

  The MAC layer belonging to L2 provides a service to an RLC (radio link control) layer, which is an upper layer, through a logical channel. The MAC layer provides a mapping function from a plurality of logical channels to a plurality of transport channels. The MAC layer provides a logical channel multiplexing function by mapping from a plurality of logical channels to a single transport channel. The MAC sublayer provides a data transfer service on the logical channel.

  The logical channel is divided into a control channel for information transmission in the control plane and a traffic channel for information transmission in the user plane according to the type of information to be transmitted. That is, a set of logical channel types is defined for different data transfer services provided by the MAC layer. The logical channel is positioned above the transport channel and mapped to the transport channel.

  The control channel is used only for information transmission in the control plane. The control channels provided by the MAC layer include BCCH (broadcast control channel), PCCH (paging control channel), CCCH (common control channel), MCCH (multicast control channel), and DCD channel. BCCH is a downlink channel for broadcasting system control information. The PCCH is a downlink channel used for paging information transmission and paging for terminals whose cell unit location is unknown to the network. The CCCH is used by the terminal when not making an RRC connection with the network. MCCH is a one-to-many downlink channel used to transmit MBMS control information from a network to a terminal. The DCCH is a one-to-one bidirectional channel used by the terminal for transmitting dedicated control information between the terminal and the network in the RRC connection state.

  The traffic channel is used only for user plane information transfer. The traffic channels provided by the MAC layer include a DTCH (Dedicated Traffic Channel) and an MTCH (Multicast Traffic Channel). The DTCH is a one-to-one channel, is used for transmitting user information of one terminal, and can exist in both uplink and downlink. The MTCH is a one-to-many downlink channel for transmitting traffic data from the network to the terminal.

  The uplink connection between the logical channel and the transport channel is DCCH that can be mapped to UL-SCH, DTCH that can be mapped to UL-SCH, and CCCH that can be mapped to UL-SCH. including. The downlink connection between the logical channel and the transport channel is BCCH that can be mapped to BCH or DL-SCH, PCCH that can be mapped to PCH, DCCH that can be mapped to DL-SCH , DTCH that can be mapped to DL-SCH, MCCH that can be mapped to MCH, and MTCH that can be mapped to MCH.

  The RLC layer belongs to L2. The functions of the RLC layer include data size adjustment by dividing / concatenating data received from the upper layer in the radio section so that the lower layer is suitable for transmitting data. In order to guarantee various QoS required by a radio bearer (RB), the RLC layer includes a transparent mode (TM), an unacknowledged mode (UM), and an acknowledged mode (AM). ) Three operation modes. AM RLC provides a retransmission function via ARQ (automatic repeat request) for reliable data transmission. Meanwhile, the functions of the RLC layer can be implemented by functional blocks inside the MAC layer, and at this time, the RLC layer may not exist.

  The PDCP (packet data convergence protocol) layer belongs to L2. The PDCP layer has a header compression function that reduces unnecessary control information so that data transmitted by introducing an IP packet such as IPv4 or IPv6 is efficiently transmitted on a wireless interface having a relatively small bandwidth. provide. Header compression increases transmission efficiency in the wireless section by transmitting only the information necessary for the data header. Further, the PDCP layer provides a security function. Security features include encryption to prevent third party inspection and integrity protection to prevent third party data manipulation.

  The RRC (radio resource control) layer belongs to L3. The RRC layer located at the bottom of L3 is defined only in the control plane. The RRC layer performs a role of controlling radio resources between the terminal and the network. For this purpose, the terminal and the network exchange RRC messages through the RRC layer. The RRC layer is responsible for controlling logical channels, transport channels, and physical channels in connection with RB configuration, re-configuration, and release. RB is a logical path provided by L1 and L2 for data transmission between the terminal and the network. That is, RB means a service provided by L2 for data transmission between the terminal and the E-UTRAN. The setting of the RB means that the radio protocol layer and the channel characteristics are defined in order to provide a specific service, and each specific parameter and operation method are determined. The RB can be divided into two, SRB (signaling RB) and DRB (data RB). The SRB is used as a path for transmitting an RRC message on the control plane, and the DRB is used as a path for transmitting user data on the user plane.

  Referring to FIG. 2, the RLC and MAC layers (finished at the eNB on the network side) can perform functions such as scheduling, ARQ, and HARQ. The RRC layer (terminated at the eNB on the network side) can perform functions such as broadcasting, paging, RRC connection management, RB control, mobility function, and terminal measurement reporting / control. NAS control protocol (terminated by MME of gateway on network side) performs functions such as SAE bearer management, authentication, LTE_IDLE mobility handling, paging start by LTE_IDLE and security control for signaling between terminal and gateway can do.

  Referring to FIG. 3, the RLC and MAC layers (finished at the eNB on the network side) can perform the same functions as those in the control plane. The PDCP layer (terminated at the network side eNB) can perform user plane functions such as header compression, integrity protection and encryption.

  The RRC state indicates whether the RRC layer of the terminal is logically connected to the RRC layer of E-UTRAN. The RRC state is divided into two, such as an RRC connection state (RRC_CONNECTED) and an RRC idle state (RRC_IDLE). If the RRC connection between the RRC layer of the terminal and the RRC layer of the E-UTRAN is set, the terminal is in the RRC connection state, otherwise the terminal is in the RRC idle state. Since the RRC_CONNECTED terminal has an RRC connection established with the E-UTRAN, the E-UTRAN can grasp the presence of the RRC_CONNECTED terminal and can effectively control the terminal. On the other hand, E-UTRAN cannot grasp the terminal of RRC_IDLE, and manages the terminal in units of tracking area (tracking area) in which the core network (CN) is larger than the cell. That is, the terminal of RRC_IDLE is known only in the unit of a larger area, and the terminal must move to RRC_CONNECTED in order to receive a normal mobile communication service such as voice or data communication.

  While the terminal designates DRX (discontinuous reception) set by NAS in the RRC_IDLE state, the terminal can receive broadcasts of system information and paging information. In addition, the terminal receives an assignment of an ID (identification) that uniquely designates the terminal in the tracking area, and can perform public land mobile network (PLMN) selection and cell reselection. Further, in the RRC_IDLE state, the RRC context is not stored in the eNB.

  In the RRC_CONNECTED state, the terminal has an E-UTRAN RRC connection and an RRC context in E-UTRAN, and can transmit data to and / or receive data from the eNB. Also, the terminal can report channel quality information and feedback information to the eNB. In the RRC_CONNECTED state, E-UTRAN can know the cell to which the terminal belongs. Therefore, the network can transmit data to the terminal and / or receive data from the terminal, and the terminal mobility (intermediate to GERAN (GSM EDGE radio access network) via handover and NCC (network assisted cell change) -RAT (radio access technology) cell change indication) can be controlled, and cell measurement can be performed for neighboring cells.

  In the RRC_IDLE state, the terminal specifies a paging DRX cycle. Specifically, the terminal monitors the paging signal at a specific paging occasion for each terminal specific paging DRX cycle. A paging opportunity is a time interval during which a paging signal is transmitted. The terminal has its own paging opportunity.

  The paging message is transmitted across all cells belonging to the same tracking area. If the terminal moves from one tracking area to another tracking area, the terminal transmits a TAU (tracking area update) message to the network in order to update the position.

  When the user first turns on the terminal, the terminal first searches for an appropriate cell and then stays in RRC_IDLE in the corresponding cell. When the RRC connection needs to be established, the terminal staying in the RRC_IDLE can establish an RRC connection with the E-UTRAN via the RRC connection procedure and move to the RRC_CONNECTED. A terminal that remains in RRC_IDLE may receive E-UTRAN when uplink data transmission is necessary due to a user's call attempt or when a paging message is received from E-UTRAN and a response message needs to be transmitted. And an RRC connection needs to be established.

  It is known that different cause values are mapped to a signature sequence used for transmitting a message between a terminal and an eNB. Furthermore, CQI (channel quality indicator) or path loss and cause or message size are known to be candidates for inclusion in the initial preamble.

  If the terminal wishes to access the network and decides to send the message, the message can be linked to the purpose and the cause value can be determined. Also, the ideal message size can be determined by identifying all additional information and different alternative sizes. A scheduling request message can be used that eliminates additional information or can be substituted.

  The terminal obtains information necessary for transmission of the preamble, UL interference, pilot transmission power, SNR required to detect the preamble at the receiver, or a combination thereof. This information must allow calculation of the initial transmit power of the preamble. In order to ensure that the same channel is used for sending messages, it is advantageous to send UL messages in the vicinity of the preamble in terms of frequency.

  In order to ensure that the network receives the preamble with a minimum SNR, the terminal must consider UL interference and UL path loss. Since UL interference can only be determined at the eNB, it must be broadcast by the eNB and received by the terminal before preamble transmission. UL path loss can be considered similar to DL path loss and can be estimated by the terminal from the received RX signal strength once the transmission power of some pilot signals of the cell is known to the terminal. .

  The UL SNR required for preamble detection typically varies with eNB configuration such as the number of Rx antennas and receiver performance. There are advantages to transmitting a somewhat static pilot transmit power, separating the required UL SNR from changing UL interference, and transmitting the possible power offset required between the message and the preamble. is there.

  The initial transmit power of the preamble can be roughly calculated by the following equation:

  Transmission power = TransmitPilot + RxPilot + UL interference + offset + SNR Required

  Thus, any combination of SNR Required, UL Interference, TransmitPilot and offset can be broadcast. In principle, only one value must be broadcast. This is essential in current UMTS systems, even though UL interference in 3GPP LTE is primarily a more neighbor cell interference than UMTS systems.

  As described above, the terminal determines the initial UL transmission power for transmitting the preamble. The eNB receiver can estimate not only the relative received power compared to the cell interference, but also the absolute received power. The eNB considers that a preamble has been detected if the received signal power compared to the interference is greater than a threshold known to the eNB.

  The terminal performs power ramping so that the preamble can be detected even when the transmission power of the initially estimated preamble is not suitable. Prior to the next random access attempt, if no ACK or NACK is received by the terminal, the other preamble is almost transmitted. In order to increase the probability of detection, the preambles can be transmitted on different UL frequencies and / or the transmission power of the preambles can be increased. Therefore, the actual transmission power of the detected preamble does not need to correspond to the initial transmission power of the preamble that is initially calculated by the UE.

  The terminal must always determine a possible UL transport format. The transport format that can include the MCS used by the terminal and a number of resource blocks is mainly determined by two parameters. Specifically, the two parameters are the eNB's SNR and the size of the message required to be transmitted.

  In practice, the maximum terminal message size, or payload, and the minimum required SNR each correspond to a transport format. In UMTS, the initial preamble transmission power estimated before transmission of the preamble, the required offset between preamble and transport block, the maximum allowable or available terminal transmission power, a fixed offset and additional It is possible to determine what transport format for transmission can be selected considering the margin. Since the network does not require time and frequency resource reservation, the preamble in UMTS need not contain any information about the transport format selected by the terminal. Thus, the transport format is displayed with the transmitted message.

  Upon receiving the preamble, after selecting the correct transport format, in order to reserve the necessary time and frequency resources, the eNB must recognize the size of the message that the terminal intends to transmit and the SNR selected by the terminal. I must. Thus, since the terminal considers several identical measurements for determining the path loss or initial preamble transmit power measured mostly in DL, the terminal transmit power compared to the maximum allowed or available terminal transmit power is Since it is not known, according to the received preamble, the eNB cannot estimate the SNR selected by the terminal.

  The eNB can calculate the difference by comparing the path loss estimated in DL and the path loss estimated in UL. However, if power ramping is used and the terminal transmission power for the preamble does not correspond to the initially calculated terminal transmission power, this calculation is not possible. Furthermore, the actual terminal transmission power and the precision of the transmission power that the terminal intends to transmit is very low. It is therefore proposed to code the path cause loss or the UL cause value with the downlink or message size CQI estimation coding or signature.

  FIG. 5 shows a scenario in which small cells are arranged with and / or without a macro area. This can be referred to Section 6.1 of 3GPP TR 36.932 V12.00 (2012-12). Small cell enhancement covers both the case where the small cell has a macro area, the case where the small cell is constructed indoors or outdoors, and whether the backhaul is ideal or non-ideal. If the small cell construction density is low, it can of course be considered high.

  Referring to FIG. 5, small cell enhancement is aimed at a scenario where small cell nodes are placed in one or more overlapping E-UTRAN macro cell hierarchical regions to increase the capacity of an already built cellular network. . Two scenarios can be considered when the terminal is in the macro cell and the small cell region at the same time and when the terminal is not in the macro cell and the small cell region at the same time. A scenario where the small cell nodes are not arranged in an area of one or more overlapping E-UTRAN macro cell hierarchies can also be considered.

  Small cell improvement aims at building small cells outdoors and indoors. Small cell nodes can be located indoors or outdoors and in each case can provide services to indoor or outdoor terminals.

  The security function will be described below.

  The security function provides integrity protection and encryption. Integrity protection prevents user data and signaling from being altered in an unauthorized manner, and encryption provides user data and signaling confidentiality.

  Hereinafter, two levels of security between the terminal and the network will be described.

  1) AS security: AS security protects RRC signaling and user data between the terminal and E-UTRAN. This provides integrity protection and encryption of RRC signaling on the control plane of the radio protocol. AS security also provides encryption of user data on the user plane of the wireless protocol. The security mode command procedure in RRC is used to activate AS security between the terminal and E-UTRAN.

  2) NAS security: NAS security protects NAS signaling between the terminal and the MME. This provides integrity protection and encryption of NAS signaling. The security mode command procedure in the NAS is used to activate the NAS security between the terminal and the MME.

  FIG. 6 shows key derivation for AS security and NAS security excluding handover.

The security function between the terminal and the network is based on a secret key called K _ASME . The K _ASME is derived from a persistent key that is stored in both the USIM (universal subscriber identity module) and the HSS (home subscriber server). The MME receives K _ASME from the HSS. The terminal derives K _ASME using the result of the AKA (authentication and key agreement) procedure with the NAS protocol. As the AKA procedure proceeds, the terminal and the network perform mutual authentication and agreement with K _ASME .

Terminal and the MME uses the K _ASME, induced K _NASint for integrity protection of NAS message, induces K _NASenc for NAS message security. The terminal and the eNB derive K _eNB from K _ASME to protect the signaling and user data on the Uu interface between them. Terminal and the eNB are derived from K _eNB, induced K _RRCint for integrity protection of RRC messages, induces K _RRCenc for encryption of RRC messages, the K _UPenc for encryption of the user data To do.

The four types of AS keys (K _eNB , K _RRCint , K _RRCenc and K _UPenc ) change at every handover and connection reconfiguration. For handover from the source eNB to the target eNB, the terminal and the source eNB induce K _eNB ^* , which is a new K _eNB used in the target cell. The other AS keys, namely K _RRCint , K _RRCenc and K _UPenc are derived from K _eNB ^* . K _eNB ^* is derived based on the current K _eNB of the terminal and the eNB, or a new NH (next hop). In addition, the physical cell ID and the downlink carrier frequency of the target cell are used for the induction of K _eNB ^* . NH is derived from K _ASME at the terminal and MME. The eNB receives NH from the MME to guide K _eNB ^* for handover. The intra cell handover procedure can be used to change the AS key during RRC_CONNECTED.

After the initial context setup procedure via the S1 interface is initiated by the MME, AS security activation is initiated by the eNB. During the initial context setup procedure, the MME provides the eNB with information on K _eNB derived directly from K _ASME for AS key guidance, integrity protection and encryption algorithms supported by the terminal. Therefore, after receiving K _eNB and the algorithm from the MME, the eNB can initialize the AS security activation of the terminal.

  FIG. 7 shows the initial activation of AS security.

  For initial activation of AS security, the eNB transmits a Security Mode Command message (S50). The SecurityModeCommand message indicates the integrity protection algorithm and the encryption algorithm to the RRC layer of the terminal after the RRC connection setup procedure is completed.

The terminal's RRC layer receives the SecurityModeCommand message to apply integrity protection before configuring the terminal's PDCP layer. Therefore, when receiving the SecurityModeCommand message, the RRC layer of the terminal decodes the SecurityModeCommand message and _derives K _RRCint using an algorithm indicated by the received SecurityModeCommand message for the integrity protection of the RRC message (S51). The RRC layer of the terminal requests the PDCP layer of the terminal to confirm the integrity of the received SecurityModeCommand message using the algorithm and K _RRCint (S52).

  It should be noted that the SecurityModeCommand message is sent with integrity protection even if AS security is not activated at the terminal. The reason is that the terminal can check the integrity of the message using an algorithm included in the message. However, encryption is not applied to the SecurityModeCommand message. The reason is that the terminal cannot decode the message until the encryption algorithm included in the message is applied.

  The PDCP layer of the terminal confirms the integrity of the SecurityModeCommand message (S53). The PDCP layer of the terminal transmits the result of the integrity check (S54). If the terminal fails to confirm the integrity of the SecurityModeCommand message, the terminal transmits a SecurityModeFailure message to the eNB in response to the SecurityModeCommand message. In this case, since an effective algorithm cannot be used in the terminal, neither integrity protection nor encryption is applied to the SecurityModeFailure message.

If the SecurityModeCommand message received in the PDCP layer of the terminal passes the integrity check, the RRC layer of the terminal further induces K _RRCenc and K _UPenc . The RRC layer of the terminal configures the PDCP layer of the terminal to apply integrity protection using the integrity protection algorithm and K _RRCint . The RRC layer of the terminal configures the PDCP layer of the terminal to apply encryption using an encryption algorithm, K _RRCenc and K _UPenc (S55). Next, the terminal assumes that AS security is activated and applies both integrity protection and encryption to all subsequent RRC messages received or transmitted by the terminal (S56).

  When AS security is activated, the RRC layer of the terminal transmits a SecurityModeComplete message to the eNB in response to the SecurityModeCommand message (S57). The SecurityModeComplete message is integrity protected but not encrypted. The reason why encryption is not applied to the SecurityModeComplete message is that whether the terminal has been successfully activated by sending two response messages (i.e., an unencrypted SecurityModeFailure message and an unencrypted SecurityModeComplete message). This is because the eNB can easily decode the response message without decoding.

  After AS security is activated, the eNB sets SRB2 and DRB. The eNB does not set SRB2 and DRB before AS security activation. When AS security is activated, all RRC messages are integrity protected and encrypted via SRB1 and SRB2. All user data is encrypted by the PDCP layer via the DRB. However, not only integrity protection but also encryption is not applied to SRB0.

  The integrity protection algorithm is common to signaling radio bearers SRB1 and SRB2, and the encryption algorithm is common to all radio bearers (ie, SRB1, SRB2 and DRB). The integrity protection and encryption algorithm can only be changed at handover.

  The SCell (secondary cell) configuration will be described.

  First, SCell addition / correction will be described. This can be referred to Section 5.3.3.10.3b of 3GPP TS 36.331 V11.1.0 (2012-09). The terminal

  1> For each sCellIndex value included in sCellToAddModeList that is not currently part of the terminal configuration (SCell addition),

  2> Add SCell corresponding to cellIdentification by received RadioResourceConfigCommonSCell and radioResourceConfigDedicatedSCell,

  2> Configure the lower hierarchy so that the SCell is considered inactive.

  1> For each sCellIndex value included in sCellToAddModeList that is part of the current terminal configuration (SCell modification),

  2> Modify the SCell configuration with the received RadioResourceConfigDedicatedSCell.

  SCell cancellation will be described. This can be referred to Section 5.3.3.10.3a of 3GPP TS 36.331 V11.1.0 (2012-09). The terminal

  1> If release is triggered by receipt of sCellToReleaseList,

  2> For each sCellIndex value included in sCellToReleaseList,

  3> If the current terminal configuration includes an SCell having an sCellIndex value,

  4> Cancel SCell.

  1> If release is triggered by RRC connection reconfiguration,

  2> Cancel all SCells that are currently part of the terminal configuration.

  Duplex connections to improve small cells are being studied. Double connection means:

  Control and data separation: For example, control signaling for mobility is provided simultaneously via the macro layer and high speed data connection is provided simultaneously via the low power layer.

  -Separation between downlink and uplink: Downlink and uplink connections are provided through different layers.

  -Diversity for control signaling: RRC signaling can be provided through multiple links, which can further improve mobility performance.

  FIG. 8 shows a dual connection scenario.

  Referring to FIG. 8, the terminal has a RRC connection with a master eNB (hereinafter, MeNB). In a dual connection, the MeNB is the eNB that controls the macro cell and terminates at least the S1-MME and therefore acts as a mobile anchor towards the CN. Also, the terminal can have a radio link with a secondary eNB (hereinafter referred to as SeNB). In a dual connection, a SeNB is a non-MeNB eNB that controls one or more small cells and provides additional radio resources for the terminal. Therefore, the terminal can receive control signaling from the MeNB and can receive data from the SeNB. MeNB and SeNB have a network interface between each other, and therefore can exchange information between each other.

  Application of security functions in a double connection has not been developed yet. Therefore, a method for applying security information in a double connection can be required.

  FIG. 9 shows an example of a method for applying security information according to an embodiment of the present invention.

  Referring to FIG. 9, the terminal acquires first security information and second security information (S100). Assume that the terminal has a first connection for signaling with the MeNB and a second connection for user traffic with the SeNB. The first connection is an RRC connection. The second connection is an L2 connection.

The first security information may be received from the MeNB via a security mode command (Security Mode Command) message. The first security information may include a first security parameter and / or a first security key. For example, the first security information can include both a first security parameter and a first security key. For example, the first security information can include only the first security parameter. In this case, the first security parameter may be received from the MeNB via a security mode command message, and the first security key may be derived based on the first security parameter. The first security key is K _RRCint , K _RRCenc or K _UPenc for _MeNB .

The second security information can be received from the MeNB via a security mode command message. The second security information can include a second security parameter and / or a second security key. For example, the second security information can include both a second security parameter and a second security key. For example, the second security information can include only the second security parameter. In this case, the second security parameter can be received from the MeNB via a security mode command message, and the second security key can be derived based on the second security parameter. The second security key is K _RRCint , K _RRCenc or K _UPenc for _SeNB .

  In the above description, the security key is applied to integrity protection or encryption. The first security parameter may include an NH (next hop) and an encryption algorithm (Encryption Algorithm). The signaling key can also be derived from the first security key along with the first security parameter. The signaling key can be used by the terminal to encrypt user traffic from the MeNB and decrypt user traffic received by the MeNB. Also, the user traffic key can be derived from the second security key along with the first security parameter or the second security parameter.

  The terminal applies the first security information to the first radio bearer (RBs) set provided from the MeNB (S110). The first security information can be applied to one or more cells of the MeNB. The terminal can encrypt the signaling transmitted from the MeNB using the first security information, and can decrypt the signaling received by the MeNB.

  The terminal applies the second security information to the second radio bearer (RBs) set provided from the SeNB (S120). The second security information can be applied to one or more cells of the SeNB. The terminal can encrypt the user traffic transmitted from the SeNB using the second security information, and can decrypt the user traffic received by the SeNB.

FIG. 10 illustrates how a terminal and a MeNB according to an embodiment of the present invention generate security keys for wireless RBs between the terminal and the macro cell. Referring to FIG. 10, the MeNB receives K _PeNB from the MME. K _PeNB is an eNB security key for the MeNB. MeNB, the two security keys for RRC message from K _PeNB, i.e., to induce K _RRCenc for encryption of K _RRCint and RRC message for integrity protection of RRC messages.

FIG. 11 illustrates how a terminal and a SeNB according to an embodiment of the present invention generate security keys for wireless RBs between the terminal and the small cell. Referring to FIG. 11, the SeNB receives K _SeNB from the MME. K _SeNB is an eNB security key for SeNB. Or SeNB receives K _SeNB from _MeNB . The SeNB then derives a security key for user traffic from K _SeNB , ie K _UPenc for encryption of user traffic.

  Hereinafter, a security mode command procedure according to an embodiment of the present invention will be described in detail.

  When the terminal is connected to both MeNB and SeNB, according to the security mode command procedure described below, the terminal receives the SecurityModeCommand message and generates a security key for both MeNB and SeNB. The terminal can receive the separated SecurityModeCommand message. The separated SecurityModeCommand message means that one is a message for MeNB and the other is a message for SeNB.

  When receiving a SecurityModeCommand message corresponding to a first group of one or more resource blocks or a first group of one or more cells from the MeNB, the terminal

1> Deriving K _eNB key for MeNB, ie K _MeNB ,

1> _{Deriving the} K _RRCint key associated with the integrityProtAlgorithm indicated by the SecurityModeCommand message

1> In order to confirm the integrity protection of the SecurityModeCommand message, use the algorithm indicated by the _{IntegrityModeCommand} message and the integrityProtAlgorithm included in the K _RRCint key, request the lower PDCP layer used for the RRC message,

  1> If the SecurityModeCommand message passes the integrity protection check,

2> _{Deriving the} K _RRCenc key associated with the ciphering _Algorithm indicated by the SecurityModeCommand message;

2> Configure the lower PDCP layer used for RRC messages immediately using the algorithm and K _RRCint key indicated for integrity protection application (ie integrity protection includes SecurityModeComplete message and is received by the terminal) , Or all subsequent messages sent)

2> After completing the procedure, configure the lower PDCP layer used in the RRC message using the algorithm and K _RRCenc key indicated for encryption application (ie, the encryption is sent unencrypted) Applied to all subsequent messages received or transmitted by the terminal except for the SecurityModeComplete message).

  2> Assuming that AS security has been activated for communication between a terminal and a cell with a MeNB (eg, PCell),

  2> Submit a SecurityModeComplete message to the lower layer for transmission, and terminate the procedure.

  1> In other cases,

  2> persist using the configuration used prior to receipt of the SecurityModeCommand message (ie, not only integrity protection, but also encryption),

  2> Submit a SecurityModeFailure message to the lower layer for transmission, and the procedure is terminated.

  After receiving the SecurityModeCommand corresponding to the MeNB from the MeNB, the terminal can receive another SecurityModeCommand corresponding to the SeNB from any one of the PeNB or SeNB. After receiving the RRC reconfiguration message that configures the SeNB cell as a serving cell, the terminal can receive the SecurityModeCommand corresponding to the SeNB.

  Instead, the Security Mode Command corresponding to the MeNB can also serve as the Security Mode Command corresponding to the SeNB. That is, one SecurityModeCommand can be used for both PeNB and SeNB.

  When receiving a SecurityModeCommand message corresponding to a second group of one or more cells or a second group of one or more RBs from the SeNB, the terminal

1> Deriving K _eNB key for SeNB, ie K _SeNB ,

  1> If the SecurityModeCommand message passes the integrity protection check,

2> _{Deriving the} K _UPenc key associated with the ciphering _Algorithm indicated by the SecurityModeCommand message,

  2> If connected to RN,

3> _{Deriving the} K _UPint key associated with the integrityProtAlgorithm indicated by the SecurityModeCommand message,

2> After completing the procedure, configure the lower PDCP layer used for user traffic using the algorithm and K _UPenc key indicated for encryption application (ie, encryption is between the terminal and SeNB) (Applies to all user traffic received or transmitted by the terminal for DRB)

  2> If connected to RN,

3> Configure the lower PDCP layer used for user traffic to apply integrity protection (if any) to _DRBs configured later using the indicated algorithm and K _UPint key And

  2> Assuming that AS security has been activated for communication between the terminal and a cell with the SeNB (eg, SCell),

  2> Submit a SecurityModeComplete message to the lower layer for transmission, and terminate the procedure.

  1> In other cases,

  2> persist using the configuration used prior to receipt of the SecurityModeCommand message (ie, encryption as well as integrity protection does not apply)

  2> Submit a SecurityModeFailure message to the lower layer for transmission, and the procedure is terminated.

  FIG. 12 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.

  The eNB 800 may include a processor 810, a memory 820, and an RF unit (radio frequency unit) 830. The processor 810 can be configured to implement the functions, processes and / or methods described herein. The hierarchy of the radio interface protocol can be implemented by the processor 810. The memory 820 is connected to the processor 810 and stores various information for driving the processor 810. The RF unit 830 is connected to the processor 810 and transmits and / or receives a radio signal.

  The terminal 900 may include a processor 910, a memory 920, and an RF unit 930. The processor 910 can be configured to implement the functions, processes and / or methods described herein. The hierarchy of the radio interface protocol can be implemented by the processor 910. The memory 920 is connected to the processor 910 and stores various information for driving the processor 910. The RF unit 930 is connected to the processor 910 and transmits and / or receives a radio signal.

  The processors 810 and 910 may include application-specific integrated circuits (ASICs), other chip sets, logic circuits, and / or data processing devices. The memories 820 and 920 may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium, and / or other storage device. The RF units 830 and 930 may include a baseband circuit for processing radio frequency signals. When the embodiment is implemented by software, the above-described technique may be implemented by modules (processes, functions, etc.) that perform the above-described functions. Modules may be stored in the memory 820, 920 and executed by the processors 810, 910. Memories 820 and 920 may be internal or external to processors 810 and 910 and may be coupled to processors 810 and 910 by various well-known means.

  In the exemplary system described above, the method that can be implemented according to the above-described features of the present invention has been described based on the flowchart. For convenience, the method has been described in a series of steps or blocks, but the claimed features of the invention are not limited to the order of steps or blocks, and some steps may differ in different steps from those described above. Or they can occur at the same time. Also, one of ordinary skill in the art will appreciate that the steps shown in the flowchart are not exclusive, other steps are included, or one or more steps in the flowchart can be deleted without affecting the scope of the invention. I can understand that.

Claims (14)

In a method of applying a security key by a terminal in a wireless communication system,
Establishing a first connection with the first eNB and a second connection with the second eNB;
Obtaining a first security key used for the first eNB;
Deriving a second security key used for the second eNB from the first security key;
Deriving a user traffic key for encryption of user traffic from the second security key;
Applying the user traffic key . The method according to claim 1, wherein the first eNB is a master eNB (MeNB), and the second eNB is a secondary eNB (SeNB) . The method of claim 2, wherein the user traffic key is K _UPenc . The method according to claim 2, wherein the second security key is for a radio bearer of the SeNB . The second security key is directed against one or more cells of the SeNB, The method of claim 2. The method of claim 2, further comprising applying the first security key . Applying the first security key comprises:
A step for deriving a signaling key for integrity protection or encryption of an RRC message from the first security key;
Applying the signaling key . The signaling key is at least one of _{K RRCint} or K _RRCenc, The method of claim 7. The method of claim 2, further comprising obtaining a first security parameter indicating a first encryption algorithm for the MeNB . The method of claim 2, further comprising obtaining a second security parameter indicating a second encryption algorithm for the SeNB . The method of claim 10, wherein the second encryption algorithm is associated with the second security key . The method of claim 2, wherein the first connection is an RRC connection for signaling . The method of claim 2, wherein the second connection is an L2 connection for user traffic . On the terminal,
Memory,
RF section;
A processor coupled to the memory and the RF unit,
The processor is
Establishing a first connection with the first eNB and a second connection with the second eNB;
Obtaining a first security key used for the first eNB;
Deriving a second security key used by the second eNB from the first security key;
Deriving a user traffic key for encryption of user traffic from the second security key; and
A terminal configured to apply the user traffic key .